An inorganic/organic hybrid perovskite compound is also referred to as an organometal halide perovskite compound or an organometal halide having a perovskite structure. The inorganic/organic hybrid perovskite compound is a substance represented by Chemical Formula of AMX3 including an organic cation (A), a metal cation (M) and a halogen anion (X), and having a perovskite structure. In detail, the inorganic/organic hybrid perovskite compound represented by Chemical Formula of AMX3 has a form in which the organic cation (A) is positioned in the middle of a three-dimensional network with a corner-sharing MX6 octahedron.
An inorganic/organic hybrid perovskite compound is self-assembled and crystallized, which is possible to perform a low temperature solution process. However, there is a serious problem in actually producing a thin film having a dense and flat surface due to rapid crystallization and difficulty in controlling self-assembling properties.
In order to solve this problem, a sequential deposition method in which films deposited with a metal halide (MX2) and an organic halide (AX) are formed, and these two films react to form an inorganic/organic hybrid perovskite compound film has been proposed (Chem. Mater. 13, 3283 (2001), Nature 499, 316 (2013)).
However, first, such a sequential deposition method has insufficient solubility of the metal halide (MX2) represented by PbI2, and thus, there is a problem in preparing a thick metal halide film. Second, even though a thick film having a thickness of 200 nm or more is obtained by applying the metal halide (MX2) solution while maintaining it at a high temperature, the reaction with AX is not sufficiently performed due to the thickness. Third, in the case of a film prepared by the conventional sequential deposition method, a large volume change occurs in the reaction of the two films, and thus, surface roughness of an inorganic/organic hybrid perovskite compound film to be finally obtained is excessively large. In particular, the roughness of the film surface may be a decisive factor in reducing a performance index when a solar cell using the inorganic/organic hybrid perovskite compound film is prepared.